New value chains – - VTT.fi | VTT - Teknologiasta tulosta value chains/Wood fractionation 28180/FFS Author(s) Pages Kari Edelmann, Juha Heikkinen, Sari Liukkonen, Veli Seppänen

$Page 1: New value chains – - VTT.fi | VTT - Teknologiasta tulosta value chains/Wood fractionation 28180/FFS Author(s) Pages Kari Edelmann, Juha Heikkinen, Sari Liukkonen, Veli Seppänen$
RESEARCH REPORT VTT-R-04772-09

New value chains –Wood fractionationAuthors: Kari Edelmann, Juha Heikkinen, Sari Liukkonen, Veli Seppänen

Confidentiality: Public

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Report’s titleNew value chains - Wood fractionationCustomer, contact person, address Order referenceFinnish Forest Cluster, EffTech -program

Project name Project number/Short nameNew value chains/Wood fractionation 28180/FFSAuthor(s) PagesKari Edelmann, Juha Heikkinen, Sari Liukkonen, Veli Seppänen 35 + appendix 24Keywords Report identification codeWood, pine, latewood, early wood, fractionation, refine VTT-R -04772-09SummaryPine logs with three different growth rates were delivered for fractionation and pulping studies from Metla’s ex-perimental plot. The logs were debarked and chipped at VTT and their average basic densities were determined.The maximum density and coarseness difference of the samples were 33 kg/ m3 and 15 µg/m. Some sample logswere also analysed at STFI Packforsk with so called Silviscan method.

The size of chips was reduced to smaller than 2 mm in thickness in order to separate the early wood from late-wood with a method developed at VTT. The resulting pin chips were then steamed and impregnated with water toremove air and to fill lumen and pores with water. Fractionation of chips was done using so called dense mediafractionation method. Density of fractionating medium was adjusted according to the desired basic density of thefractions. Concentrated sodium sulphate solution was used as fractionating medium. Continuously operated pro-totype fractionation equipment was used for fractionation trials.

According to the results dense media fractionation can be used to increase basic density and coarseness differ-ence of pin chips. The maximum basic density and coarseness difference were 150 kg/m3 and respectively50µg/m. The mechanical pulping trials revealed that density is very important raw material parameter in terms ofenergy consumption and pulp quality. The energy consumption difference of the fractions was 47 %. Fractiona-tion increased also the surface roughness and density difference of paper samples.

Also standard cooking trials of the fractions were done, but only for medium growth rate fractions. Yield andbrightness differences between fractions were measured, but more studies should be done to conclude the differ-ences. Optimised cooking conditions of fractions should reveal larger fibre level differences.

As the next step, larger scale fractionation trials with commercial equipment followed by pilot scale mechanicaland chemical pulping are proposed. Fractionation should also be considered as a multi-stage process. DM frac-tionation may be used to

- narrow the variation of raw material properties,- reduce energy consumption and costs of fibre production,- broaden the properties of fibre supply,- deliver new product characteristics.

Confidentiality PublicJyväskylä 12.8.2009Written by

Kari Edelmann, research professor

Reviewed by

Terhi Saari, customer manager

Accepted by

Janne Poranen, technology man-ager

VTT’s contact addressPO Box 1603, 40101 Jyväskylä

Distribution (customer and VTT)Finnish Forest Cluster, authors, VTT archive

The use of the name of the VTT Technical Research Centre of Finland (VTT) in advertising or publication in partof this report is only permissible with written authorisation from the VTT Technical Research Centre of Finland.

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Preface

This report is a part of the research project, which was carried out by VTT, KCL and Metlaand financed by the Finnish Forest Cluster Ltd. The project is part of EffTech-program,started in 2008 and terminated in 2009.

This final report summarises the results of the fractionation and refining studies made at VTT.Research Professor Kari Edelmann was responsible of the VTT's subproject in New valuechains -project. Research Professor Kari Edelmann, Senior Research Scientist Veli Seppänenand Research Scientist Juha Heikkinen are responsible in writing this report. TechnicianJouko Aalto was responsible in planning and construction of the chip cleaving test rig, B.Sc.(Eng) Ismo Tiihonen, Research Assistant Jorma Ihalainen and Senior Research Scientist VeliSeppänen were responsible for carrying out the cleaving experiments, Research AssistantJorma Ihalainen and Research Scientist Juha Heikkinen were responsible in dense media frac-tionation and thermo mechanical refining trials. Research Assistant Riitta Pöntynen was re-sponsible in analysis at VTT.

Some properties of the wood samples were analysed at STFI Packforsk and results calculatedat Metla. Researcher Harri Mäkinen from Metla was responsible for the calculations.

Chemical pulp cooking experiments were carried out at KCL from the materials delivered byVTT. Mrs Sari Liukkonen was responsible for the cooking experiments.

Jyväskylä, 12.8.2009

Authors

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Contents

Preface ........................................................................................................................3

1 Introduction.............................................................................................................51.1 Variation of basic density ................................................................................51.2 Variation of fibre length ...................................................................................81.3 Variation of moisture content ..........................................................................81.4 Effect of the wood material on the properties of mechanical pulps .................9

2 Goal......................................................................................................................10

3 Description............................................................................................................103.1 Devices .........................................................................................................103.2 Samples........................................................................................................12

4 Limitations ............................................................................................................13

5 Methods................................................................................................................135.1 Characterization of wood samples ................................................................135.2 Fractionation of wood....................................................................................14

6 Results .................................................................................................................156.1 Characterisation of wood samples ................................................................156.2 Fractionation of wood....................................................................................156.3 Fibre and paper properties and SEC in mechanical pulping .........................226.4 Cooking experiments ....................................................................................28

6.4.1 Results...............................................................................................297 Validation of results ..............................................................................................31

8 Summary ..............................................................................................................32

References ................................................................................................................35

Appendix 1.................................................................................................................36Characterisation of wood samples........................................................................36Fractionation of wood ...........................................................................................41Mechanical pulping experiments ..........................................................................50Cooking experiments............................................................................................57

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1 Introduction

Physical properties of wood vary due to soil conditions, climate conditions, genetic proper-ties, silviculture and many other things. The variation of physical properties increases with thedecreasing sample size; that is from mill scale to cutting area, stem and annual ring. The im-portant properties that affect on pulping properties are basic density, fibre length distributionand moisture content. The content of extractives is supposed to affect on specific energy con-sumption (SEC) in refining (Reme 2000, p. 104). The extent of the variation of these proper-ties is summarised in the next sections.

Figure 1. Effect of the extractives in refining (Reme 2000, p. 104).

1.1 Variation of basic density

The average basic densities of Scots pine saw mill and pulp chips used in some Finnish papermills are presented in Figure 2. The range of variation is roughly 20 kg/m3 by pulp chips and40 kg/m3 by saw mill chips.

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Figure 2. The average basic density (=kuivatuoretiheys) of Scots pine saw mill chips (left)and pulp wood (right) at confidence level 95 %. (Lindblad & Verkasalo 2001, p.421).

The practical variation of basic density in wood samples is however much larger, as it can beseen in Figure 3. The average basic density for pulp wood chips is 406 kg/m3 ranging from390 to 420 kg/m3. Saw mill chips have a little bit higher basic density values than pulp woodchips (Lindblad & Verkasalo 2001, p. 426).

Figure 3. The basic density distribution of Scots pine saw mill chips (left) and pulp woodchips (right). (Havaintoja (kpl) =number of observations) (Lindblad & Verka-salo 2001, p. 416).

Within a stem, the basic density of wood changes both in radial and longitudinal directions, asshown in Figure 4 and 5.

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Figure 4. The variation pattern of average wood basic density in the longitudinal direc-tion of the stem in Finland; Birch, Pine and Spruce (Hakkila 1966, p 41).

Figure 5. Basic density of wood (Scots pine) as a function of distance from pith in dataset1 (diamonds) and dataset 2 (triangles) (Kärenlampi & Riekkinen 2004, p. 467).

As the result of the variation pattern of wood basic density, raw material and fibre propertiesof pine vary in a very large range depending on the age and growth rate of the tree and on thelocation of a wood sample within a stem.

The growth rate, a factor that determines the mechanical strength properties of wood, can eas-ily be determined visually from a cross section of a tree. The density of growth rings is de-

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pendent on growth conditions. At microscopic level, the growth ring consists of large, thincell wall fibres (early wood) and smaller, thick cell wall fibres (latewood). In average, theamount of latewood fibre in pine in top wood is about 21 % (Rikala 2003, p 64).

1.2 Variation of fibre length

The fibre length increases from pith to sap wood and decreases from butt to top. It is interest-ing to find out that old sapwood have longer fibre length compared with sapwood of youngerfinal cutting or second thinning trees.

In average slowly grown wood has longer fibre length than fast grown wood.

Fibre length correlates strongly with fibre coarseness (Sirviö & Kärenlampi 1996, p 19).

1.3 Variation of moisture content

Inside a stem, moisture content increases from butt to top, Figure 6. Moisture content is muchhigher in sapwood (60 % wet basis) than in heart wood (25 %). Moisture content of woodmay also change due to varying storage times of stems and chips. Moisture content of woodvaries also with season; in summer time around 39 % and at Christmas around 50 %. Thesemoisture content variations all together make problems in sorting of logs or chips according tobasic density.

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Figure 6. Variation in the average green moisture content (dry Basis) along the stemheight in Norway spruce and Scots pine (Tyrväinen 1995, p 29).

1.4 Effect of the wood material on the properties of mechanical pulps

Correlation between wood properties and TMP pulp properties has been widely studied(Tyrväinen 1995, Reme 2000, Liukkonen & Sirviö 2006, Hartler 1985). Hartler has concludedthat TMP -pulp from high basic density wood results in lower tensile index than from lowerbasic density wood, Figure 7.

Figure 7. Effect of wood density on tensile index of spruce TMP according to Hartler(1985). All tensile index values are at 100 ml freeness (CSF) level.

The significance of early and latewood fibres in papermaking has been studied by sortingstem wood according to its diameter and growth rate. Papermaking properties and energyconsumption differences between early wood rich juvenile and latewood rich mature woodare significant. In refining, mature wood (longer and thicker wall fibres) absorbs energy moreeasily than forest thinning wood (shorter and thinner wall fibres) (Tyrväinen 1995, Nyblom1979 and Hartler 1985).

Delamination (or peeling of the outer layers) of rigid fibres is very important for paper qual-ity, as fibres having cell wall thickness greater than 4 µm do not collapse in the papermakingprocess (Forseth 1997). Thick wall fibres will also increase roughness of paper when treatedwith water (Hallamaa et al. 23.6.1998). Tensile index of the long fibre fraction can be in-creased 100% by reducing the amount of thick wall fibres from 10 to 4 % (Koljonen & Heik-kurinen 1995).

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2 Goal

The objective of this study was to produce fractions with large basic density difference thoughuse of dense media fractionation method. The further objectives were to use these fractions inmechanical and chemical pulping and to analyse the respective fibre properties and to deter-mine the potential of fractionation in saving energy and chemicals. Lab scale fractionationmethods and pine samples with different growth rates were used in the study.

3 Description

3.1 Devices

Knife mill was used to cleave pulp chips into chips thinner than 2 mm. The cleaving separatesrather effectively early wood (EW) from latewood (LW). A continuously operated processwas set up to maximise the separation efficiency of EW, Figure 8.

CleavingPocket

Rollscreening

Recycling of large particles

Pulp chips

Pin chips

Figure 8. Principle of the pin chip process.

The equipment consisted of a feeder pin, belt conveyors, knife mill and Pocket Roll screen,Figure 9.

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Figure 9. Continuous cleaving and screening process for pulp chips. 1 = feeding of pulpchips, 2 = conveyor of cleaved chips, 3 = feeding pulp chips and cleaved chipson screen, 4 = Pocket Roll screen, 5 =conveyor of oversize chips, 6 = knife-mill,7 =magnet, 8 =conveyor of accepted pin chips.

After separation of EW from wood chips, the target was to find out how EW pin chips couldbe separated into its own fraction as pure as possible. So called dense media fractionationmethod was used, Figure 10. The equipment is shown in the Figure 11.

Figure 10. Principle of the EW/LW fractionation concept.

FractionationDense media

separation (DMS)

Cleavingwith knife mill

Impregnationwith water

Recoveryof separation

medium washing

DM storageincluding density

controlSolid Na2SO4

or Na2SO3or Na2CO3

Recoveryof separation

medium washingLight fraction

Heavy fraction

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Figure 11. Continuous dense media fractionation.

The pin chips were refined by VTT’s wing refiner, Figure12.

Figure 12. Wing refiner; 1 = Feeding channel, 2 = pre-heating of chips, 3 = feeding piston,4 = refiner, 5 =pressure control, 6 =control panel.

3.2 Samples

Metla (Forest Research Institute) provided pine logs with three different growth rates. Topwood samples of 150 – 60 mm in diameter were used in the trials.

d M

Feeder

A B

A B

N D

L

Dense media in

Pin chips in

LW fraction out

EW fraction out

D=142 mmL=950 mmM=68 mmN=50 mm

Vibrator

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4 Limitations

Only three basic density classes were used in the studies. Each basic density class consisted ofpulp wood parts of two stems.

Fractionation trials have been done in laboratory scale using single stage fractionation. Theresults have been used in a way that may be achieved through two stage fractionation.

Mechanical and chemical pulping trials have been done batch-wise in laboratory scale.

5 Methods

5.1 Characterization of wood samples

The sample trees were characterized by measuring

the breast height diameter,height of the tree,the height to diameter 6 cm,branch diameterliving branch or dead,number of annual rings of the sample logs,diameter of the sample logs,annual rings of each cut,basic densities of sample discs of each log,bark content,moisture content of bark and wood.

The fibre properties of the sample discs were analysed by Silviscan, an automated scanning x-ray micro-densitometer/image analyser, (Evans et al. 1993). In Figure 13, we can see thatcoarseness values are rather similar within annual rings, but density has large variation. Den-sity is low in the beginning of the growth season and high at the end of growth season.

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Figure 13. Example of Silviscan measurement (Evans et al. 1993).

5.2 Fractionation of wood

So called dense media fractionation technique was used to fractionate wood raw material. DMfractionation has been used in industrial scale to fractionate coal and plastics. The first step isto separate early wood and latewood into separate particles. Because the annual rings in pineare only 1-3 mm in thickness, the particles have to be smaller in thickness than the annualrings.

The sample logs were debarked manually, chipped with TT1000TU disc chipper, cleavedwith knife mill and screened with modified Pocket Roll screen for pin chips.

To get right density differences for early wood pin chips and latewood pin chips the lumenshave to be filled with water. Therefore the pin chips were steamed and impregnated with wa-ter.

Steaming of pin chips was done in a pressure vessel at 104 C temperature and in 0.4 barpressure for 15 minutes. After steaming, warm water (50 C/0.3 bar) was fed trough the vesselfor 15 minutes. After impregnation the pin chips were stored in plastic bags, at 5 C for fur-ther use. The impregnated and stored pin chips were laid 30 minutes in water before fractiona-tion, if the storage time is more than 6 hours.

Stationary preliminary fractionation trials with different dense media were done in 1.5 litrestatic beaker using concentrated Na2SO4 solution. Density of the solution was chosen in a waythat the pin chips separate into floating and sinking fractions after mixing the impregnated pinchips into the medium. After 2 minutes of mixing photograph was taken and fractions werecollected and washed with pure water to remove traces of saline solution and then weightedwith respect to their yields. Yield of the floating fraction was dependent on the density of themedium.

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Continuously operated lab-scale fractionation equipment was used for fractionation trials,Figure 11. The suitable operation parameters were studied with pre-studies:

dense media density levels 1075, 1115 and 1160 kg/m3

slope of fractionator 20velocity of dense media 2,67 litres/stemperature of dense media 35–40 Cfractionation capacity 20 kg (DS)/h.

The exact values of each trial point are presented in the result Table 1.

The following properties of the fractions and fed pin chips were measured:

basic densityfibre propertiesparticle length and width distributionrefining properties

SEC (Specific Energy Consumption)/tRRmfibre properties of accepted fractionspaper properties of accepted fractions

6 Results

All experimental results are shown in the appendix 1 and only main results are presented inthe following text.

6.1 Characterisation of wood samples

The sample trees were harvested from two different experiments and from tree different ex-perimental plots. The trees 126 and 235 were fast grown, trees 35 and 72 medium grown andtrees 21 and 129 slowly grown.

6.2 Fractionation of wood

Before fractionation, the pulp chips were processed into pin chips. The particle thickness wasanalysed by mechanical screen and the distributions are presented in the Figure 14. Less than8 % of the pin chips are thicker than 2 mm. 42–50 % belongs to classes 0–1 mm and 1–2 mmin thickness. Only small differences, but not significant, appear in different growth rateclasses.

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0

10

20

30

40

50

60

>4 mm 2-4 mm 1-2 mm 0-1 mm

SlowMediumFast

Figure 14. Particle thickness distribution of the pin chips.

Another particle size measurement was done by image analysis. The length and width distri-butions of pin chips are presented in Figures 15-17. Original pin chips were rather similar inlength and width. The greatest difference was noticed between latewood fraction from slowlygrown wood and early wood fraction from fast grown wood. Early wood fractions are longerand thicker than latewood fractions.

0

5

10

15

20

25

30

0-0,5 0,5-1 1-1,5 1,5-2 2-2,5 2,5-3 >3

Width class, mm

Popo

rtio

n of

the

wid

th c

lass

, %

SlowMediumFast

Figure 15. Width of unfractionated pin chips.

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0

5

10

15

20

25

30

35

0-0,5 0,5-1 1-1,5 1,5-2 2-2,5 2,5-3 >3

Width class, mm

Prop

ortio

n of

the

wid

th c

lass

, %

Slow LWFast EWMedium LWMedium EW

Figure 16. Width of fractionated pin chips.

0

5

10

15

20

25

30

35

0-0,5 0,5-1 1-1,5 1,5-2 2-2,5 2,5-3 >3

Width class, mm

Popo

rtio

n of

the

wid

th c

lass

, %

MediumMedium LWMedium EW

Figure 17. Width of fractionated medium grown pin chips.

Preliminary studies were done in a beaker, Figure 18. Medium density had a clear effect onsinking. Based on the preliminary studies the conditions of dynamic trials were chosen. Thefinal conditions were chosen from the pre-trials with dynamic equipment. The trial conditionsand main fractionation results are presented in the Table 1.

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Figure 18. Experiments were done in static beaker by Na2SO4 solution. The amount of solu-tion was 1.5 litres and pin chips 20 g dry.

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Table 1. Fractionation conditions and main results.

Experiment MaterialValve

position

Density ofNA2SO4

solutionCyclone

angle

Velosity ofDensemedia

Moisturecontent of feed

pin chips

Share ofEW

fraction Capasitynro o kg/m3 o litre/s % % (DS) kg (DS)/h4 P35 + P72 medium 47 1190 20 2,68 69,3 88 7,55 P35 + P72 medium 47 1160 20 2,68 71,0 75 8,26 P35 + P72 medium 47 1113 20 2,68 71,0 47 7,813 P35 + P72 medium 47 1074 20 2,68 71,0 17 6,97 P126 + P235 fast 47 1115 20 2,67 74,8 54 6,88 P126 + P235 fast 47 1075 20 2,68 74,8 22 7,89 P126 + P235 fast 47 1147 20 2,67 74,8 74 9,210 P21 + P129 slow 47 1157 20 2,67 73,2 81 8,011 P21 + P129 slow 47 1111 20 2,68 73,2 50 9,212 P21 + P129 slow 47 1072 20 2,67 73,2 18 7,714 P35 + P72 medium 47 1075 20 2,67 71,0 19 7,115 P35 + P72 medium 47 1158 20 2,67 71,0 76 7,416 P21 + P129 slow 49 1160 20 2,68 73,2 68 7,317 P126 + P235 fast 49 1074 20 2,68 74,8 16 7,2

KCL 1 P35 + P72 medium 49 1076 20 2,67 60,0 13 7,9KCL 2 P35 + P72 medium 49 1166 20 2,67 60,0 62 8,3

FeedEearlywood Latewood Feed Early wood Latewood Feed

Earlywood Latewood Feed Early wood Latewood

nro kg/m3 kg/m3 kg/m3 mm mm mm µm µm µm µg/m µg/m µg/m4 369,0 1,85 34,85 369,0 367,7 471,9 1,85 1,83 1,77 34,8 35,1 33,5 156 152 1716 369,0 344,4 456,4 1,85 1,85 1,83 34,8 35,5 34,3 156 148 16813 369,0 317,5 394,5 1,85 1,78 1,86 34,8 35,3 34,6 156 137 1617 356,0 330,4 421,8 1,72 1,71 1,69 33,8 33,9 32,6 143 139 1478 356,0 314,9 386,1 1,72 1,66 1,69 33,8 34,4 33,3 143 138 1429 356,0 353,1 462,1 1,72 1,69 1,72 33,8 33,8 32,2 143 144 15810 389,0 372,0 467,6 1,81 1,90 1,70 36,2 36,4 34,3 158 156 17311 389,0 344,2 437,0 1,81 1,83 1,81 36,2 36,6 35,4 158 157 17312 389,0 313,9 395,6 1,81 1,70 1,79 36,2 36,2 35,5 158 148 16414 369,0 320,0 418,8 1,85 1,78 1,87 34,8 34,7 34,0 156 129 14315 369,0 382,2 476,9 1,85 1,88 1,80 34,8 34,6 33,6 156 150 15916 389,0 364,4 426,2 1,81 1,81 1,75 36,2 35,5 34,9 158 154 16717 356,0 311,0 371,6 1,72 1,59 1,64 33,8 34,8 33,3 143 124 143

KCL 1 369,0 320,9 403,5 1,85 1,71 1,87 34,8 34,9 34,4 156 138 163KCL 2 369,0 371,9 441,9 1,85 1,74 1,70 34,8 34,7 34,0 156 155 170

Coarseness

Experiment

Basic density Fibre length Fibre width

Basic density of fractions and original pin chips are presented in Figure 19 and 20. The largestdifference in basic density was 165 kg/m3. That is between early wood fraction from fastgrown wood and latewood fraction from slowly grown wood. In original logs, the greatestbasic density difference was between fast and slowly grown logs, and that was 33 kg/m3.

Basic density of fractions

280290300310320330340350360370380390400410420430440450460470480490500

1050 1060 1070 1080 1090 1100 1110 1120 1130 1140 1150 1160 1170 1180 1190 1200

Dense media density, kg/m3

Bas

ic d

ensi

ty, k

g/m

3

Medium_early woodMedium_latewoodFast_early woodFast_latewoodSlow_early woodSlow_latewoodMedium_pin chipsFast_pin chipsSlow_pin chipsLinear (Medium_pin chips)Linear (Fast_pin chips)Linear (Slow_pin chips)Linear (Medium_early wood)Linear (Fast_early wood)Linear (Fast_latewood)Linear (Medium_latewood)Linear (Slow_latewood)Linear (Slow_early wood)

Early wood fraction ~ 20 %DS

Late wood fraction ~ 80 %DS

Slow growing

Medium growing

Fast growing

Late wood fraction ~ 50 %DS Late wood fraction ~ 20 %DS

Early wood fraction ~ 50 %DS Early wood fraction ~ 80 %DS

KCL-1 (EWt) =320,9 kg/m3

KCL-2 (LW) =441,9 kg/m3

Figure 19. Basic densities of fractions versus dense media density.

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280290300310320330340350360370380390400410420430440450460470480490500

0 10 20 30 40 50 60 70 80 90 100Early wood fraction,%

Bas

ic d

ensi

ty, k

g/m

3



Late wood fraction ~ 80 %DS Late wood fraction ~ 50 %DS Late wood fraction ~ 20 %DS


KCL trials; feedmaterial = 369 kg/m3

KCL- 2 (LW) = 441,9kg/m3

KCL -1 (EW) = 320,9 kg/m3

Slow

Medium

Fast

Figure 20. Basic densities of fractions versus separated early wood fraction.

Coarseness values of the fractions and original pin chips are presented in the Figure 21. Thedifference of coarseness value in one stage fraction varies between 4-25 µg/m. The largestdifference in coarseness 49 µg/m was noticed between early wood fraction from fast grownwood and latewood fraction from slowly grown wood. In original logs, the largest coarsenessdifference was between fast and slowly grown logs, and that was 15 µg/m. The results arerather logical, because in the most cases one of the fractions have lower coarseness value thanthe original pin chips and while the other fraction has higher coarseness value.

Coarseness of fractions

120

130

140

150

160

170

180

1050 1060 1070 1080 1090 1100 1110 1120 1130 1140 1150 1160 1170 1180 1190 1200


Coa

rsen

ess,

µg/

m

Medium_early woodMedium_latewoodFast_early woodFast_latewoodSlow_early woodSlow_latewoodMediumFastSlowLinear (Medium_latewood)Linear (Medium_early wood)Linear (Medium)Linear (Fast)Linear (Slow)Linear (Fast_latewood)Linear (Fast_early wood)Linear (Slow_early wood)Linear (Slow_latewood)

Slow

Medium

Fast

Figure 21. Coarseness of fractions versus dense media density.

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The fibre length results of the fractionation trials are presented in the Figure 22. The resultsare not logical in the cases when the both fraction have shorter fibre length than the originalpin chips. However, differences are small and inside the sampling and analysis limits.

Fibre length of fractions

1,5

1,6

1,7

1,8

1,9

2,0

1050 1060 1070 1080 1090 1100 1110 1120 1130 1140 1150 1160 1170 1180 1190 1200


Fibr

e le

ngth

, mm


Slow

Mediumgrown

Fastgrow

Figure 22. Fibre length in fractionation trials.

The fibre width results of the fractionation trials are presented in the Figure 23.

Fibre width of fractions

30

31

32

33

34

35

36

37

38

39

40

1050 1070 1090 1110 1130 1150 1170 1190


Fibr

e w

idth

, µm


Slow grown

Medium grown

Fast grown

Figure 23. Fibre width in fractionation trials.

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6.3 Fibre and paper properties and SEC in mechanical pulping

Specific energy consumption (SEC) of different growth rate pine samples in TMP-refining ispresented in the Figure 24. Refining of fast grown pine consumes more energy than slowlygrown.

Specific energy consumption of medium grown pine and its early and latewood fractions arepresented in Figure 25. The differences are very small, but it seems that refining of earlywood fraction consumes more energy than latewood fraction. The result is analogous with theresult of refining different growth rate pin chips.

VTT wing refiner; Blades RS10/SL30-90, clockwise rotation, blade gap 0,5 mm,2500 rpm, preheated 120 oC, pressure 2,5 bar

3000

3500

4000

4500

5000

5500

6000

6500

7000

7500

8000

8500

9000

9500

0 50 100 150 200 250CF, ml

SEC

, kW

h/t

MediumSlowFastPower (Medium)Power (Slow)Power (Fast)

Figure 24. SEC in refining different growth rate pine pin chips.

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VTT wing refiner; Blades RS10/SL30-90, clockwise rotation, blade gap 0,5 mm,2500 rpm, preheated 120 C, pressure 2,5 bar

3000

3500

4000

4500

5000

5500

6000

6500

7000

7500

8000

8500

9000

0 50 100 150 200 250 300 350CF, ml

SEC

, kW

h/t

Medium EW (Koe 14)Medium LW (Koe 15)MediumPower (Medium EW (Koe 14))Power (Medium LW (Koe 15))Power (Medium)

Figure 25. SEC in refining medium grown pine pin chips.

Very large specific energy consumption difference, 47 %, was achieved when comparing therefining behaviour of slowly grown latewood with that of fast grown early wood, Figure 26.

3000

3500

4000

4500

5000

5500

6000

6500

7000

7500

8000

8500

9000

9500

0 50 100 150 200CF, ml

SEC

, kW

h/t Slow LW (Koe 16)

Fast EW (Koe 17)Power (Fast EW (Koe 17))Power (Slow LW (Koe 16))


Figure 26. Maximal difference in SEC.

Growth rate and fractionation had only a very small effect on fibre length of screened pulp,Figure 27.

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1,00

1,10

1,20

1,30

1,40

1,50

20 30 40 50 60 70 80 90 100CFaccept, ml

Fibr

e le

ngth

, mm

Medium EWSlow LWMedium LWFast EWMediumSlowFast

Figure 27. Fibre lengths of accepted pulps.

Pitäisikö tässä välissä kertoa, että jauhetuista massoista tehtiin laboratorioarkit (60 gsm? ,kiertovesi) ja määritettiin paperitekniset (viittaus standardiin mitä käytetty), olisi loogista,koska nämä on mainittu myös sellunvalmistusosiossa.

Refined early wood fraction and fast grown pine have higher laboratory sheet density than thesheets from slowly grown pine or early wood fraction, Figure 28.

25 (59)

300

320

340

360

380

400

420

440

20 30 40 50 60 70 80 90 100CFaccept, ml

Labo

rato

ry s

heet

den

sity

, kg/

m3

Medium EWMedium LWFast EWSlow LWMediumSlowFast

Figure 28. Density of the laboratory sheets.

Early wood fraction and fast grown wood had higher bendability than medium or slowlygrown wood and latewood fraction, Figure 29.

1,00

1,50

2,00

2,50

3,00

3,50

20 30 40 50 60 70 80 90 100CFaccept, ml

Ben

dabi

lity


Figure 29. Bendability.

Pulp from early wood fraction had lower roughness at the same freeness level than pulps fromun-fractionated or latewood fractions, Figure 30.

26 (59)

0

50

100

150

200

250

300

350

400

450

500

20 30 40 50 60 70 80 90 100CFaccept, ml

Ben

dtse

n ro

ughn

ess,

ml/m

in (B

otto

m s

ide)


Figure 30. Bendtsen roughness.

0

20

40

60

80

100

120

140

160

20 30 40 50 60 70 80 90 100CFaccept, ml

Air

Perm

eanc

e, m

l/min

(Bot

tom

sid

e)


Figure 31. Air permeability.

Pulps from early wood fraction had higher tensile index at the same freeness level than pulpsfrom un-fractionated or latewood fractions, Figure 32. The result is consistent with the litera-ture, see Figure 7.

27 (59)

25

30

35

40

45

50

20 30 40 50 60 70 80 90 100CFaccept, ml

Tens

ile in

dex,

Nm

/g Medium EWSlow LWMedium LWFast EWMediumSlowFast

Figure 32. Tensile index.

Lower basic density results low roughness, Figure 33.

0

50

100

150

200

250

300

350

400

450

500

300 350 400 450 500

Basic density, kg/m3

Ben

dtse

n ro

ughn

ess,

ml/m

in (B

otto

m s

ide)


Late wood

Early wood

Originalwood

Figure 33. Bendtsen roughness vs. basic density.

Low Bendtsen roughness requires a lot of refining energy, Figure 34.

28 (59)

3000

4000

5000

6000

7000

8000

9000

10000

0 50 100 150 200 250 300 350 400 450 500Bendtsen roughness, ml/min (Bottom side)

SEC

, kW

h/t


Figure 34. SEC vs. Bendtsen roughness.

6.4 Cooking experiments

The aim of the cooking experiments was to examine how the cooking of early wood and late-wood rich pine fraction differs from each other.

The raw materials for the cooking trials were delivered to KCL by VTT. The samples weremore like pin chips or sawdust than normal chips. The three samples and their basic densitieswere:

reference (ref) 366 kg/m3

early wood rich fraction (ew) 321 kg/m3

latewood rich fraction (lw) 442 kg/m3

First, the H-factor series were done for all the three samples. Later, the accuracy of the yieldresults was checked by air drying the wood samples to have more even sample for the dry sol-ids content determination and weighing, and thus more reliable results. In these tests the targetkappa numbers were 25 and 30. The air dried samples were kept in water in room temperaturefor half an hour before cooking.

After the cookings, the pulps were disintegrated in a British disintegrator, washed with de-ionized water, screened with a TAP 03 laboratory screen (0.15 mm slot), centrifuged and ho-mogenized. Determinations were made for total yield, screenings, kappa number (ISO 302)and brightness (ISO 2470:99). The black liquors were analyzed for pH and residual alkali(SCAN-N 33:94). From three samples (kappa 25) viscosity (SCAN-CM 15:99), fibre length(Kajaani FS300), density (ISO 5270:1998), tensile (ISO 5270:1998) and tear (ISO 5270:1998)were determined.

29 (59)

6.4.1 Results

The cooking report is shown in the Table 2 and the pulp properties in the Table 3.Table 2. Cooking report.BASIC DATA

Order No. CookingNo.

Date Cookingmethod

Chipmark

Dry mattercontent

EA Sulfidity L/W Cookingtemp.

H-factor Yield Shives Totalyield

Kappanumber

Brightness pH Residualalkali

% mol/kg % % °C % % % % gNaOH/l2005-302 1744M 4.3.2009 Purukeitto ref 40.0 6 35 4.5 180 800 45.2 0.05 45.2 35.7 33.1 13.4 15.42005-302 1750M 9.3.2009 Purukeitto ref 40.0 6 35 4.5 180 950 44.1 0.03 44.2 28.1 34.8 13.4 15.22005-302 1753M 9.3.2009 Purukeitto ref 40.0 6 35 4.5 180 1050 43.6 0.05 43.7 24.7 35.6 13.4 13.72005-302 1747M 4.3.2009 Purukeitto ref 40.0 6 35 4.5 180 1200 43.3 0.02 43.3 23.4 36.6 13.4 13.12005-302 1746M 4.3.2009 Purukeitto ew 31.2 6 35 4.5 180 800 44.1 0.02 44.2 38.8 36.8 13.4 16.52005-302 1752M 9.3.2009 Purukeitto ew 31.2 6 35 4.5 180 950 43.5 0.07 43.5 33.3 38.0 13.4 16.62005-302 1755M 9.3.2009 Purukeitto ew 31.2 6 35 4.5 180 1050 42.9 0.09 43.0 27.8 39.7 13.4 15.62005-302 1749M 4.3.2009 Purukeitto ew 31.2 6 35 4.5 180 1200 42.4 0.03 42.4 24.7 41.0 13.4 13.92005-302 1745M 4.3.2009 Purukeitto lw 40.9 6 35 4.5 180 800 42.8 0.04 42.9 32.6 37.8 13.4 16.02005-302 1751M 9.3.2009 Purukeitto lw 40.9 6 35 4.5 180 950 42.0 0.06 42.1 26.8 39.8 13.4 15.62005-302 1754M 9.3.2009 Purukeitto lw 40.9 6 35 4.5 180 1050 41.7 0.10 41.8 24.5 40.7 13.4 15.02005-302 1748M 4.3.2009 Purukeitto lw 40.9 6 35 4.5 180 1200 41.0 0.01 41.1 20.6 42.6 13.4 13.92005-302 1766M 1.4.2009 Purukeitto ref dry 91.8 6 35 4.5 180 900 44.4 0.04 44.5 28.8 32.8 13.3 14.42005-302 1769M 1.4.2009 Purukeitto ref dry 91.8 6 35 4.5 180 1050 43.8 0.06 43.8 25.7 34.0 13.2 13.32005-302 1768M 1.4.2009 Purukeitto ew dry 90.1 6 35 4.5 180 1000 42.6 0.04 42.6 27.1 39.1 13.3 15.22005-302 1771M 1.4.2009 Purukeitto ew dry 90.1 6 35 4.5 180 1200 42.0 0.04 42.0 22 41.5 13.3 13.82005-302 1767M 1.4.2009 Purukeitto lw dry 91.9 6 35 4.5 180 850 42.8 0.06 42.9 29 38.7 13.3 15.82005-302 1770M 1.4.2009 Purukeitto lw dry 91.9 6 35 4.5 180 1050 41.8 0.04 41.8 24.3 40.7 13.3 14.0

CHIP DATA CHEMICAL CHARGE TEMPERATURE PULP BLACK LIQUOR

30 (59)

Table 3. Pulp properties.Ew Ref Lw

SampleNumber of

tests 1749 m1753 m1754 mWet disintegration of chemical pulp ISO 5263-1:2004Fibre distribution, FS-300 - Arithmetic av. fibre length, mm 0.70 0.79 0.72 - Length weighted av. fibre length, mm 1.53 1.66 1.54 - Weight weighted av. fibre length, mm 2.13 2.26 2.19 - Length < 0,2 mm, % 5.36 4.17 4.46 - Fiber curl, % 7.5 7.7 7.1 - Kink index, 1/m 350 375 349 - Fiber width, µm 24.8 25.1 24.8Grammage, g/m² *) ISO 5270:1998 66.1 66.3 66.4Bulking thickness, µm *) ISO 5270:1998, ISO 534:1988 5 87.4 100 106Standard deviation, µm 1.7 2 3Apparent bulk-density, kg/m³ *) ISO 5270:1998, ISO 534:1988 5 756 661 629Standard deviation, kg/m³ 14 13 15Bulk, cm³/g *) ISO 534:1988 5 1.32 1.51 1.59Standard deviation, cm³/g 0.03 0.03 0.04Tensile strength, kN/m *) ISO 5270:1998, EN ISO 1924-2:1994 10 5.84 4.48 4.10Standard deviation, kN/m 0.25 0.17 0.13Tensile index, Nm/g *) ISO 5270:1998, EN ISO 1924-2:1994 10 88.4 67.5 61.7Standard deviation, Nm/g 3.8 2.6 1.9Stretch, % *) ISO 5270:1998, EN ISO 1924-2:1994 10 2.6 2.3 2.2Standard deviation, % 0.2 0.2 0.1Tensile energy absorption, J/m² *) EN ISO 1924-2:1994 10 103 70.0 62.9Standard deviation, J/m² 12 9.1 5.0TEA index, J/g *) EN ISO 1924-2:1994 10 1.57 1.06 0.948Standard deviation, J/g 0.18 0.14 0.075Tensile stiffness, kN/m *) EN ISO 1924-2:1994 10 606 511 483Standard deviation, kN/m 10 11 14Tensile stiffness index, kNm/g *) EN ISO 1924-2:1994 10 9.17 7.70 7.27Standard deviation, kNm/g 0.16 0.17 0.21Modulus of elasticity, N/mm² *) EN ISO 1924-2:1994 10 6934 5095 4571Standard deviation, N/mm² 120 111 129Tearing strength, mN *) ISO 5270:1998, ISO 1974:1990 5 583 833 881Standard deviation, mN 14 24 40Tear index, mNm²/g *) ISO 5270:1998, ISO 1974:1990 5 8.82 12.6 13.3Standard deviation, mNm²/g 0.21 0.4 0.6

Arrival date:25.5.2009Date of tests: 26.5.2009/askTest conditions: 50% RH, 23°CApproval: 26.5.2009 ELK

Compared at a constant H-factor, the lw-fraction was cooked to lower kappa number than ew-fraction (Fig. 35). When air-dried raw materials were use, the difference was much smaller.The yield of lw-pulps was lower than that of ew-pulps (Fig. 36 left). Both fractions gotsmaller yield than the reference indicating that something was lost or some reactions havetaken place during the fractionation and washing processes. This has also affected the higherbrightness of the fraction-pulps (Fig. 36 right).

The viscosities of the pulps at kappa level 25 were 920 (ref), 890 (ew) and 900 (lw) indicatingthat the yield loss is not because of excess dissolving of hemicelluloses (the viscosity of thefraction-pulps is not higher than that of the reference).

31 (59)

20

25

30

35

40

700 800 900 1000 1100 1200 1300

Ka

pp

a n

um

be

r

H-factor

refref dryewew drylwlw dry

Figure 35. Kappa number as a function of H-factor.

40

41

42

43

44

45

46

20 25 30 35 40

Yie

ld %

Kappa number


30

35

40

45

20 25 30 35 40

Bri

gh

tne

ss %

Kappa number


Figure 36. Total yield and pulp brightness as a function of kappa number.

Both fraction-pulps had 0.1 mm lower fibre length than the reference, Table 4. In general, se-vere fibre cutting has taken place already during the preparation of the pin chips (initial fibrelength ca. 2.5 mm). The density of the laboratory sheets made of ew-pulp had much higherdensity, higher tensile and lower tear index than the lw-pulp. In general, the lw-pulp proper-ties were closer to the reference pulp, but the ew-pulp was clearly different.Table 4. Fiber length and sheet properties of the cooked pulps.

Sample ref ew lwFiber length, lw, FS300, mm 1.66 1.53 1.54Apparent bulk-density, kg/m³ 661 756 629Tensile index, Nm/g 67.5 88.4 61.7Stretch, % 2.3 2.6 2.2Tear index, mNm²/g 12.6 8.82 13.3

7 Validation of results

The pin chips production process is reliable. The production capacity (about 500 kg DS/h)was in the level which had steady flow.

32 (59)

Fractionation process is stable. The STDEV of dense media flow has measured in earlier stud-ies to be 0.07 l/s, STDEV of dense media density 5.4 kg/m3 and STDEV of early wood frac-tion proportion 3.1 %-units when fractionated 30 % EW/70 % LW. The difference of basicdensity in parallel analysis has been 2.2-7.1 kg/m3. Analysis error (tn95) has been 5 kg/m3. Weconclude that the fractionation process is very stable. The measured difference in dense mediafractionation (60-100 kg/m3) is significant.

The pulps were screened by FS-03 (# 0.13 mm slotted screens, profile 1.1 mm). The analysisresults are expected to be reliable, even though the results do not represent the properties ofwhole pulp. The number of laboratory sheets analysed in each point is 5-7 and standard is 10.Breaking index is not measured because of too small number of sheet. Other paper propertiesare considered to be reliable.

The wood sample in each growth rate includes only pulp wood part of two stems. That israther small. Besides, the slowly grown stems had large difference in basic density betweenthe stems. The result is not statistically reliable, but only suggestive.

Refining trials are made in laboratory scale by VTT wing refiner. The refining conditionswere not optimized for each fraction, but refined in same conditions. The results should beverified in larger scale.

The cooking trials were made in laboratory scale and only with two fractionation samples.The fractions had not the maximum difference in basic density and the samples were not thesame, which had the maximum difference in mechanical refining. The cooking trials are onlyintroductory.

8 Summary

Pine logs with three different growth rates were delivered for fractionation and pulping stud-ies from Metla´s experimental plot. The logs were debarked and chipped at VTT and their av-erage basic densities were determined. The maximum density and coarseness difference of thesamples were 33 kg/ m3 and respectively 15 µg/m in the sample logs. Some sample logs werealso analysed at STFI Packforsk with so called Silviscan method.

The size of chips was reduced to <2 mm in thickness in order to separate the early wood fromlatewood with a method developed at VTT. The resulting pin chips were then steamed andimpregnated with water (to remove air and to fill lumen and pores with water). Fractionationof chips was done using so called dense media fractionation method. Density of fractionatingmedium was adjusted according to the desired basic density of the fractions. Concentratedsodium sulphate solution was used as fractionating medium. Continuously operated prototypefractionation equipment was used for fractionation trials.

According to the results dense media fractionation can be used to increase basic density andcoarseness difference of pin chips. The maximum basic density difference between 20 % oflightest and 20 % heaviest fraction was 150 kg/m3 that is respectively in industrial wood 40kg/m3. The coarseness difference in the respective fractions was 50 µg/m.

The mechanical pulping trials revealed that density is very important raw material parameterin terms of energy consumption and pulp quality. The greatest energy consumption difference

33 (59)

of the fractions was 47 %. Fractionation increased also the surface roughness and density dif-ference of paper samples.

Also standard cooking trials of the fractions were done, but only for medium growth rate frac-tions. Yield and brightness differences between fractions were measured, but more studiesshould be done to conclude the differences. Optimised cooking conditions of fractions shouldreveal larger fibre level differences.

The cooking of latewood fraction to certain kappa number required shorter cooking time thancooking of ew-fraction. The pulp properties were close to the reference. Instead, the earlywood pulp had clearly different pulp properties: higher density, higher tensile and lower tear.

These were the first cooking experiments with this kind of wood fractions. Definite conclu-sions cannot be drawn based on these few tests. In the future, more experiments should bedone to ascertain the results. Reference raw material, which is treated similarly as the refer-ences, should be tested. In addition, it should be studied what happens during the fractionationand washing (loss of certain substances or particles, reactions, etc.). Comparison to cookingwith normal chips should be done as well, although the optimal cooking conditions for normalchips and pin chips/sawdust are different.

Further, the bleachability and beatability of the pulps, and the effect on paper properties inblend sheets could be examined. Effect on surface properties of the paper is one issue of inter-est, including the effect on calendering.

Fractionation of Norway spruce has been studied earlier using a single-stage dense mediafractionation concept. This study implies that dense media fractionation may offer several ad-vantages to homogenize the pulping material, improve the efficient fibre production, broadenthe properties of fibre supply and offer new product characteristics for fibre based products.

As the next step, larger scale fractionation trials with commercial equipment followed by pilotscale mechanical and chemical pulping are proposed. Fractionation should also be consideredas a multi-stage process (Figure 37). Dense media fractionation may be used to

- homogenization of pulping raw material,- reducing energy consumption and costs of fibre production,- broadening the properties of fibre supply,- delivering new fibre product characteristics.

Energy and chemical saving potential is proposed to be studied by mixing mechanical andchemical pulps at different freeness levels produced from different fractions. Early wood frac-tion should be refined to higher freeness level than latewood fraction and save energy in thisway.

34 (59)

1-stage fractionation

DM fractionation 1Low basic density

High basic density

Pin chips

2-stage fractionation

DM fractionation 1Low basic density

High basic density Medium basic density

Pin chips

Figure 37. Principles and 1- or 2-stage fractionation process.

35 (59)

ReferencesEvans, R., Downes, G., Menz, D: & Stringer S. 1995. Rapid measurement of variation in tracheid transverse di-

mensions in a radiata pine tree. Pp. 134-138. (Apita Vol 48 No 2.)

Forseth, T.E.F. 1997. Moisture – induced roughening of paper containing mechanical pulp, Doctor Thesis. Trond-heim: Norwegian University of Science and Technology.

Hakkila, P. 1966. Investigation on the basic density of Finnish pine, spruce and birch wood. Pp. 1-98. (Communi-cationes Institut Forestalis Fenniae 61.)

Hartler, N. 1985. Wood quality requirements, process adaptation and necessary sacrifice. Proc. International Me-chanical Pulping Conference, Stockholm, May 6-10, 1985. Pp 109-119.

Koljonen, T., Heikkurinen, A. 1995. Delamination of stiff fibres. International Mechanical Pulping Conference, Ot-tawa, Canada, 12-15 June 1995. Pp. 79-84.

Kärenlampi, P. P. & Riekkinen M. 2004. Maturity and growth rate effects on Scots pine basic density. Wood SciTechnol. (2004)38. ed. Springer-Verlag. Pp. 465-473.

Lindblad, J., Verkasalo, E. 2001. Teollisuus- ja kuitupuuhakkeen kuiva-tuoretiheys ja painomittauksen muuntoker-toimet. Metsätieteen aikakauskirja (3/2001). Pp. 411–431.

Liukkonen, S., Sirviö, J. 31.5.2006. Effect of spruce properties on TMP refining. 5th Fundamental MechanicalPulp Research Seminar, Trondheim 2006. 9 p.

Nyblom, I. 1979. Kuitupuun laadun merkitys mekaanisen massan valmistuksen kannalta. Metsätehon raaka –ainepäivät, Jyväskylä, November 6-7, 1979. Mimeograph. 13 p.

Reme, P. A. 2000. Some effects of wood characteristics and the pulp process on mechanical pulp fibres. NTNU,Norvege: 120 p.

Rikala, J. 2003. Spruce and pine on drained peatlands - wood quality and suitability for the sawmill industry. Uni-versity of Helsinki, Department of Forest Resource Management. 147 p. ( Publications 35.)

Sirviö, J., Kärenlampi, P. 1996. Puukuitujen ominaisuuksia jakaumia ja korrelaatioita. Helsinki: Helsingin Yliopisto.57 p. ISBN 951-45-7455-9

Tyrväinen, J. 1995. Wood and Fibre Properties of Norway Spruce and Its Suitability for Thermomechanical Pulp-ing. The Finnish Society of Forest Science - The Finnish Forest Research Institute: Acta Forestalia Fen-nica 249. 155 p. ISBN 951-40-1479-0

36 (59) Appendix 1

Appendix 1

Characterisation of wood samples

The sample trees were harvested from two different experiments and from tree different ex-perimental plots, Table 5. The trees 126 and 235 were fast grown, trees 35 and 72 mediumgrown and trees 21 and 129 slowly grown. The fast grown trees had thickest branches andless dead branches.

The properties of the samples are in Table 6. The bark content in the sample logs was 10 %(green weight-%). The moisture content of wood was 40 % and bark 37 %.

Table 5. Sample trees.

Experiment Experimentalplot

Growthrate

Treenumber

Heightof thetree

D1,3 Branchdiameter

Deadbranches

m cm mm %

126 26,7 38,7509 2 Fast

235 24,9 34,7

39 0

35 25,2 24,2509 1 Medium

72 23,2 23,2

19,4 90

21 19,1 20512 7 Slow

129 17,9 20,4

15,9 63

37 (59) Appendix 1

Table 6. Properties of the sample trees.D

iam

eter

und

er th

eba

rk, m

m

Ann

ual r

ings

Aw

erag

e an

nual

grow

th, m

m

Bas

ic d

ensi

ty o

f the

sam

ple

disc

, kg/

m3

Dia

met

er u

nder

the

bark

, mm

Ann

ual r

ings

Aw

erag

e an

nual

grow

th, m

m

Bas

ic d

ensi

ty o

f the

sam

ple

disc

, kg/

m3

P72-1 147,5 27 2,73 368 126,5 377 245 372P72-2 126,5 23 2,75 377 106,5 369 257 373P72-3 106,5 18 2,96 369 89,5 367 242 368P72-4 89,5 14 3,20 367 43,5 7 3,11 335 189 351P35-1 142,5 24 2,97 399 117,5 404 257 402P35-2 117,5 18 3,26 404 95,5 381 247 393P35-3 95,5 16 2,98 381 54 8 3,38 368 228 375

Medium 3,04 376P126-1 147 16 4,59 356 96,5 355 250 355P126-2 96,5 12 4,02 355 54,5 5 5,45 353 243 354P235-1 148,5 21 3,54 377 111,5 362 264 369P235-2 111,5 17 3,28 362 59 10 2,95 364 254 363

Fast 3,97 360P21-1 142,5 31 2,30 413 125 397 279 405P21-2 125 25 2,50 397 94 391 271 394P21-3 94 22 2,14 391 60,5 9 3,36 380 271 386

P129-1 147 30 2,45 370 127,5 361 228 365P129-2 127,5 25 2,55 361 94 353 256 357P129-3 94 18 2,61 353 53 8 3,31 326 271 340Slow 2,65 374

Basicdensity of

the log,kg/m3N

umbe

r of t

he lo

g

But end of the pulp wood log Top end of the log

Leng

th o

f the

log,

cm

At STFI Packforsk radius increment (Figure 38), wood density (Figure 39), early wood den-sity (Figure 40), latewood density (Figure 41 ), latewood % (Figure 42) and density distribu-tion (Figure 43) were measured by Silviscan.

38 (59) Appendix 1

0

1

2

3

4

5

6

7

8

0 10 20 30 40 50 60 70

Annual ring

Rad

ial i

ncre

men

t, m

m

509,1,35 509,1,72 509,2,126 509,2,235 512,7,21 512,7,129

Figure 38 . Annual growth in the direction of radius The first annual ring is the nearest inthe core.

300

350

400

450

500

550

600

650

700

750

800

0 10 20 30 40 50 60 70

Annual ring

Woo

d de

nsity

, kg/

m3

509,1,35 509,1,72 509,2,126 509,2,235 512,7,21 512,7,129

Figure 39. The density in the direction of radius.

39 (59) Appendix 1

250

270

290

310

330

350

370

390

410

430

450

0 10 20 30 40 50 60 70

Annual ring

Early

woo

d de

nsity

, kg/

m3

509,1,35 509,1,72 509,2,126 509,2,235 512,7,21 512,7,129

Figure 40. The density of early wood.

500

600

700

800

900

1000

1100

1200

1300

0 10 20 30 40 50 60 70

Annual ring

Late

woo

d de

nsity

, kg/

m3

509,1,35 509,1,72 509,2,126 509,2,235 512,7,21 512,7,129

Figure 41. The density of latewood.

40 (59) Appendix 1

0 %

10 %

20 %

30 %

40 %

50 %

60 %

70 %

0 10 20 30 40 50 60 70

Annual ring

Late

woo

d, %

509,1,35 509,1,72 509,2,126 509,2,235 512,7,21 512,7,129

Figure 42. Latewood percentage.

Density distribution of the sample stems

0

5

10

15

20

25

30

35

40

-200

200-2

50

250-3

00

300-3

50

350-4

00

400-4

50

450-5

00

500-5

50

550-6

00

600-6

50

650-7

00

700-7

50

750-8

00

800-8

50

850-9

00

900-9

50

950-1

000

1000

-

Density, kg/m3

Shar

e of

the

sam

ple

disc

, %

Slowly 21Slowly 64Medium 35Medium 72Fast 126Fast 235

Figure 43. Density distribution of different trees. Analysed by Silviscan at STFI.

41 (59) Appendix 1

Table 7. Fibre properties of the sample trees.

0.0-0.2mm

0.2-0.5mm

0.5-1.2mm

1.2-2.0mm

2.0-3.2mm >3.2 mm

mm µm % % % % % % µg/mSlow 2,51 36,2 87,1 0,23 0,42 66,7 9,45 5,5 4,0 6,7 18,8 43,6 21,3 147

Medium 2,59 34,9 86,7 0,23 0,44 66,9 9,8 5,4 3,5 5,7 16,5 45,9 22,9 135Fast 2,40 33,8 87,0 0,25 0,43 65,9 9,8 5,0 3,8 7,5 21,1 46,5 16,0 137

Growthrate Coarseness

Fibre length classes

Kink/mm

LengthWeightedAverageShape

LengthWeightedAverage

Width

LengthWeightedAverageLength

LengthWeightedAverage

BendabilityKink AngleKink/fiber

Fractionation of wood

Before fractionation, the pulp chips were processed into pin chips. The particle thickness wasanalysed by mechanical screen and the distributions are presented in the Figure 14. Less than8 % of the pin chips are thicker than 2 mm. 42–50 % belongs to classes 0–1 mm and 1–2 mmin thickness. Only small differences, but not significant, appear in different growth rates.

0

10

20

30

40

50

60

>4 mm 2-4 mm 1-2 mm 0-1 mm

SlowMediumFast

Figure 44. Particle thickness distribution of the pin chips.

Another particle size analyse was done by image analysis. The length and width distributionsare presented in Figures 45-49. Original pin chips are rather similar in length and width. Thegreatest difference is between latewood fraction from slowly grown wood and early woodfraction from fast grown wood. Early wood fractions are longer and thicker than latewoodfractions.

42 (59) Appendix 1

0

10

20

30

40

50

60

70

80

90

100

0 5 10 15 20 25

Pin chip length, mm

Cum

ulat

ive

shar

e of

the

volu

me,

%

SlowMediumFastSlow LW20Fast EW20Medium LWMedium EW

Figure 45. Length of the pin chips.

0

10

20

30

40

50

60

70

80

90

100

0 0,5 1 1,5 2 2,5 3 3,5 4 4,5

Pin chip width, mm

Cum

ulat

ive

shar

e of

the

volu

me.

%

SlowMediumFastSlow LW20Fast EW20Medium LWMedium EW

Figure 46. Width of the pin chips.

43 (59) Appendix 1

0

5

10

15

20

25

30

0-0,5 0,5-1 1-1,5 1,5-2 2-2,5 2,5-3 >3

Width class, mm

Prop

ortio

n of

the

wid

th c

lass

, %

SlowMediumFast

Figure 47. Width of unfractionated pin chips.

0

5

10

15

20

25

30

35

0-0,5 0,5-1 1-1,5 1,5-2 2-2,5 2,5-3 >3

Width class, mm

Prop

ortio

n of

the

wid

th c

lass

, %

Slow LWFast EWMedium LWMedium EW

Figure 48. Width of fractionated pin chips.

44 (59) Appendix 1

0

5

10

15

20

25

30

35

0-0,5 0,5-1 1-1,5 1,5-2 2-2,5 2,5-3 >3

Width class, mm

Prop

ortio

n of

the

wid

th c

lass

, %

MediumMedium LWMedium EW

Figure 49. Width of fractionated medium grown pin chips.

Densities of pin chips were measured in 0,5 x 0,5 x 0,5 m box. The results are shown in Table8. The results are rather close to each other. The dry densities of slowly grown should behighest, but perhaps the growing conditions are different to others because it is from differentexperiment plant.Table 8. Densities of pin chips measured in 0,5 x 0,5 x 0,5 m box.Growth rate Moisture content Green density Dry density Green density after 3 drop Dry density after 3 drop

% kg/m3 kg/m3 kg/m3 kg/m3Slow 54,0 282 130 322 148Fast 55,1 291 131 342 154

Medium 52,3 278 133 332 158

Preliminary studies were done in static beaker, Figure 50. Medium density had a clear effecton sinking. Based on the preliminary studies the conditions of dynamic trial were chosen. Thefinal conditions were chosen from the pre-trials with dynamic equipment. The trial conditionsand main fractionation result are presented in the Table 9.

45 (59) Appendix 1

Figure 50. Experiments were done in static beaker by Na2SO4 solution. The amount of solu-tion was 1.5 litres and pin chips 20 g dry.

46 (59) Appendix 1

Table 9. Fractionation conditions and main results.

Experiment MaterialValve

position

Density ofNA2SO4

solutionCyclone

angle

Velosity ofDensemedia

Moisturecontent of feed

pin chips

Share ofEW

fraction Capasitynro o kg/m3 o litre/s % % (DS) kg (DS)/h4 P35 + P72 medium 47 1190 20 2,68 69,3 88 7,55 P35 + P72 medium 47 1160 20 2,68 71,0 75 8,26 P35 + P72 medium 47 1113 20 2,68 71,0 47 7,813 P35 + P72 medium 47 1074 20 2,68 71,0 17 6,97 P126 + P235 fast 47 1115 20 2,67 74,8 54 6,88 P126 + P235 fast 47 1075 20 2,68 74,8 22 7,89 P126 + P235 fast 47 1147 20 2,67 74,8 74 9,210 P21 + P129 slow 47 1157 20 2,67 73,2 81 8,011 P21 + P129 slow 47 1111 20 2,68 73,2 50 9,212 P21 + P129 slow 47 1072 20 2,67 73,2 18 7,714 P35 + P72 medium 47 1075 20 2,67 71,0 19 7,115 P35 + P72 medium 47 1158 20 2,67 71,0 76 7,416 P21 + P129 slow 49 1160 20 2,68 73,2 68 7,317 P126 + P235 fast 49 1074 20 2,68 74,8 16 7,2

KCL 1 P35 + P72 medium 49 1076 20 2,67 60,0 13 7,9KCL 2 P35 + P72 medium 49 1166 20 2,67 60,0 62 8,3

FeedEearlywood Latewood Feed Early wood Latewood Feed

Earlywood Latewood Feed Early wood Latewood

nro kg/m3 kg/m3 kg/m3 mm mm mm µm µm µm µg/m µg/m µg/m4 369,0 1,85 34,85 369,0 367,7 471,9 1,85 1,83 1,77 34,8 35,1 33,5 156 152 1716 369,0 344,4 456,4 1,85 1,85 1,83 34,8 35,5 34,3 156 148 16813 369,0 317,5 394,5 1,85 1,78 1,86 34,8 35,3 34,6 156 137 1617 356,0 330,4 421,8 1,72 1,71 1,69 33,8 33,9 32,6 143 139 1478 356,0 314,9 386,1 1,72 1,66 1,69 33,8 34,4 33,3 143 138 1429 356,0 353,1 462,1 1,72 1,69 1,72 33,8 33,8 32,2 143 144 15810 389,0 372,0 467,6 1,81 1,90 1,70 36,2 36,4 34,3 158 156 17311 389,0 344,2 437,0 1,81 1,83 1,81 36,2 36,6 35,4 158 157 17312 389,0 313,9 395,6 1,81 1,70 1,79 36,2 36,2 35,5 158 148 16414 369,0 320,0 418,8 1,85 1,78 1,87 34,8 34,7 34,0 156 129 14315 369,0 382,2 476,9 1,85 1,88 1,80 34,8 34,6 33,6 156 150 15916 389,0 364,4 426,2 1,81 1,81 1,75 36,2 35,5 34,9 158 154 16717 356,0 311,0 371,6 1,72 1,59 1,64 33,8 34,8 33,3 143 124 143

KCL 1 369,0 320,9 403,5 1,85 1,71 1,87 34,8 34,9 34,4 156 138 163KCL 2 369,0 371,9 441,9 1,85 1,74 1,70 34,8 34,7 34,0 156 155 170

Coarseness

Experiment

Basic density Fibre length Fibre width

Basic density of fractions and original pin chips is presented in Figure 51 and 52. The largestdifference in basic density was 165 kg/m3. That is between early wood fraction from fastgrown wood and latewood fraction from slowly grown wood. In original logs, the greatestbasic density difference was between fast and slowly grown logs, and that was 33 kg/m3.

47 (59) Appendix 1


280290300310320330340350360370380390400410420430440450460470480490500

1050 1060 1070 1080 1090 1100 1110 1120 1130 1140 1150 1160 1170 1180 1190 1200


Bas

ic d

ensi

ty, k

g/m

3



Late wood fraction ~ 80 %DS

Slow growing

Medium growing

Fast growing

Late wood fraction ~ 50 %DS Late wood fraction ~ 20 %DS


KCL-1 (EWt) =320,9 kg/m3

KCL-2 (LW) =441,9 kg/m3

Figure 51. Basic densities of fractions versus dense media density.


280290300310320330340350360370380390400410420430440450460470480490500

0 10 20 30 40 50 60 70 80 90 100Early wood fraction,%

Bas

ic d

ensi

ty, k

g/m

3



Late wood fraction ~ 80 %DS Late wood fraction ~ 50 %DS Late wood fraction ~ 20 %DS


KCL trials; feedmaterial = 369 kg/m3

KCL- 2 (LW) = 441,9kg/m3

KCL -1 (EW) = 320,9 kg/m3

Slow

Medium

Fast

Figure 52. Basic densities of fractions versus separated early wood fraction.

Coarseness values of the fractions and original pin chips are presented in the Figure 53. Thedifference of coarseness value in one stage fraction varies between 4-25 µg/m. The largestdifference in coarseness 49 µg/m, was noticed between early wood fraction from fast grown

48 (59) Appendix 1

wood and latewood fraction from slowly grown wood. In original logs, the largest coarsenessdifference was between fast and slowly grown logs, and that was 15 µg/m. The results arerather logical, because in the most cases the one fraction have lower coarseness value than theoriginal pin chips and the another fraction has higher coarseness value.

Coarseness of fractions

120

130

140

150

160

170

180

1050 1060 1070 1080 1090 1100 1110 1120 1130 1140 1150 1160 1170 1180 1190 1200


Coa

rsen

ess,

µg/

m


Slow

Medium

Fast

Figure 53. Coarseness of fractions versus dense media density.

The fibre length results of the fractionation trials are presented in the Figure 54. The resultsare not logical in the cases when the both fraction have shorter fibre length than the originalpin chips. However, differences are small and inside the sampling and analysis limits.

49 (59) Appendix 1

Fibre length of fractions

1,5

1,6

1,7

1,8

1,9

2,0

1050 1060 1070 1080 1090 1100 1110 1120 1130 1140 1150 1160 1170 1180 1190 1200


Fibr

e le

ngth

, mm


Slow

Mediumgrown

Fastgrow

Figure 54. Fibre length in fractionation trials.

The fibre width results of the fractionation trials are presented in the Figure 55.

Fibre width of fractions

30

31

32

33

34

35

36

37

38

39

40

1050 1070 1090 1110 1130 1150 1170 1190


Fibr

e w

idth

, µm


Slow grown

Medium grown

Fast grown

Figure 55. Fibre width in fractionation trials.

50 (59) Appendix 1

Mechanical pulping experiments

Specific energy consumption (SEC) of different growth rate pine samples in TMP-refining ispresented in the Figure 56. Refining of fast grown pine consumes more energy than slowlygrown.

In Figure 57, is compared the SEC of medium grown pine and its early and latewood frac-tions. The differences are very small, but it seems that refining of early wood fraction con-sumes more energy than latewood fraction. The result is analogous with the result of refiningdifferent growth rate pin chips.

VTT wing refiner; Blades RS10/SL30-90, clockwise rotation, blade gap 0,5 mm,2500 rpm, preheated 120 oC, pressure 2,5 bar

3000

3500

4000

4500

5000

5500

6000

6500

7000

7500

8000

8500

9000

9500

0 50 100 150 200 250CF, ml

SEC

, kW

h/t

MediumSlowFastPower (Medium)Power (Slow)Power (Fast)

Figure 56. SEC in refining different growth rate pine pin chips.

51 (59) Appendix 1


3000

3500

4000

4500

5000

5500

6000

6500

7000

7500

8000

8500

9000

0 50 100 150 200 250 300 350CF, ml

SEC

, kW

h/t

Medium EW (Koe 14)Medium LW (Koe 15)MediumPower (Medium EW (Koe 14))Power (Medium LW (Koe 15))Power (Medium)

Figure 57. SEC in refining medium grown pine pin chips.

Very large specific energy consumption difference, 47 %, was achieved when comparing therefining behaviour of slowly grown latewood with that of fast grown early wood, Figure 58.

3000

3500

4000

4500

5000

5500

6000

6500

7000

7500

8000

8500

9000

9500

0 50 100 150 200CF, ml

SEC

, kW

h/t Slow LW (Koe 16)

Fast EW (Koe 17)Power (Fast EW (Koe 17))Power (Slow LW (Koe 16))


Figure 58. Maximal difference in SEC.

Growth rate and fractionation had only a very small effect on fibre length of screened pulp,Figure 59.

52 (59) Appendix 1

1,00

1,10

1,20

1,30

1,40

1,50

20 30 40 50 60 70 80 90 100CFaccept, ml

Fibr

e le

ngth

, mm


Figure 59. Fibre lengths of accepted pulps.

Refined early wood fraction and fast grown pine have higher laboratory sheet density than thesheets from slowly grown pine or early wood fraction, Figure 60.

300

320

340

360

380

400

420

440

20 30 40 50 60 70 80 90 100CFaccept, ml

Labo

rato

ry s

heet

den

sity

, kg/

m3

Medium EWMedium LWFast EWSlow LWMediumSlowFast

Figure 60. Density of the laboratory sheets.

Growth rate or fractionation did not have effect on shape factor, Figure 61.

53 (59) Appendix 1

85

90

95

20 30 40 50 60 70 80 90 100CFaccept, ml

Shap

e fa

ctor


Figure 61. Shape factor.

Early wood fraction and fast grown wood had higher bendability than medium or slowlygrown wood and latewood fraction, Figure 62.

1,00

1,50

2,00

2,50

3,00

3,50

20 30 40 50 60 70 80 90 100CFaccept, ml

Ben

dabi

lity


Figure 62. Bendability.

54 (59) Appendix 1

Pulp from early wood fraction had lower roughness at the same freeness level than pulps fromun-fractionated or latewood fractions, Figure 63.

0

50

100

150

200

250

300

350

400

450

500

20 30 40 50 60 70 80 90 100CFaccept, ml

Ben

dtse

n ro

ughn

ess,

ml/m

in (B

otto

m s

ide)


Figure 63. Bendtsen roughness.

Air permeability is in Figure 64.

0

20

40

60

80

100

120

140

160

20 30 40 50 60 70 80 90 100CFaccept, ml

Air

Perm

eanc

e, m

l/min

(Bot

tom

sid

e)


Figure 64. Air permeability.

55 (59) Appendix 1

Pulps from early wood fraction had higher tensile index at the same freeness level than pulpsfrom un-fractionated or latewood fractions, Figure 65. The result is consistent with the litera-ture, see Figure 7.

25

30

35

40

45

50

20 30 40 50 60 70 80 90 100CFaccept, ml

Tens

ile in

dex,

Nm

/g Medium EWSlow LWMedium LWFast EWMediumSlowFast

Figure 65. Tensile index.

Growth rate or fractionation did not have effect on brightness, Figure 66.

50

55

60

65

70

20 30 40 50 60 70 80 90 100CFaccept, ml

R45

7 (b

otto

m s

ide)


56 (59) Appendix 1

Figure 66. Brightness (R457).

Lower basic density results low roughness, Figure 67.

0

50

100

150

200

250

300

350

400

450

500

300 350 400 450 500

Basic density, kg/m3

Ben

dtse

n ro

ughn

ess,

ml/m

in (B

otto

m s

ide)


Late wood

Early wood

Originalwood

Figure 67. Bendtsen roughness vs. basic density.

Low Bendtsen roughness requires a lot of refining energy, Figure 68.

3000

4000

5000

6000

7000

8000

9000

10000

0 50 100 150 200 250 300 350 400 450 500Bendtsen roughness, ml/min (Bottom side)

SEC

, kW

h/t


Figure 68. SEC vs. Bendtsen roughness.

57 (59) Appendix 1

Cooking experiments

The aim of the cooking experiments was to examine how the cooking of early wood and late-wood rich pine fraction differs from each other.

The raw materials for the cooking trials were delivered to KCL by VTT. The samples weremore like pin chips or sawdust than normal chips. The three samples and their basic densitieswere:reference (ref) 366 kg/m3

early wood rich fraction (ew) 321 kg/m3

latewood rich fraction (lw) 442 kg/m3

First, the H-factor series were done for all the three samples. Later, the accuracy of the yieldresults was checked by air drying the wood samples to have more even sample for the dry sol-ids content determination and weighing, and thus more reliable results. In these tests the targetkappa numbers were 25 and 30. The air dried samples were kept in water in room temperaturefor half an hour before cooking.

After the cooks, the pulps were disintegrated in a British disintegrator, washed with de-ionized water, screened with a TAP 03 laboratory screen (0.15 mm slot), centrifuged and ho-mogenized. Determinations were made for total yield, screenings, kappa number (ISO 302)and brightness (ISO 2470:99). The black liquors were analyzed for pH and residual alkali(SCAN-N 33:94). From three samples (kappa 25) viscosity (SCAN-CM 15:99), fibre length(Kajaani FS300), density (ISO 5270:1998), tensile (ISO 5270:1998) and tear (ISO 5270:1998)were determined.

The cooking report is shown in the Table 10 and the pulp properties in the Table 11.Table 10. Cooking report.BASIC DATA

Order No. CookingNo.

Date Cookingmethod

Chipmark

Dry mattercontent

EA Sulfidity L/W Cookingtemp.

H-factor Yield Shives Totalyield

Kappanumber

Brightness pH Residualalkali

% mol/kg % % °C % % % % gNaOH/l2005-302 1744M 4.3.2009 Purukeitto ref 40.0 6 35 4.5 180 800 45.2 0.05 45.2 35.7 33.1 13.4 15.42005-302 1750M 9.3.2009 Purukeitto ref 40.0 6 35 4.5 180 950 44.1 0.03 44.2 28.1 34.8 13.4 15.22005-302 1753M 9.3.2009 Purukeitto ref 40.0 6 35 4.5 180 1050 43.6 0.05 43.7 24.7 35.6 13.4 13.72005-302 1747M 4.3.2009 Purukeitto ref 40.0 6 35 4.5 180 1200 43.3 0.02 43.3 23.4 36.6 13.4 13.12005-302 1746M 4.3.2009 Purukeitto ew 31.2 6 35 4.5 180 800 44.1 0.02 44.2 38.8 36.8 13.4 16.52005-302 1752M 9.3.2009 Purukeitto ew 31.2 6 35 4.5 180 950 43.5 0.07 43.5 33.3 38.0 13.4 16.62005-302 1755M 9.3.2009 Purukeitto ew 31.2 6 35 4.5 180 1050 42.9 0.09 43.0 27.8 39.7 13.4 15.62005-302 1749M 4.3.2009 Purukeitto ew 31.2 6 35 4.5 180 1200 42.4 0.03 42.4 24.7 41.0 13.4 13.92005-302 1745M 4.3.2009 Purukeitto lw 40.9 6 35 4.5 180 800 42.8 0.04 42.9 32.6 37.8 13.4 16.02005-302 1751M 9.3.2009 Purukeitto lw 40.9 6 35 4.5 180 950 42.0 0.06 42.1 26.8 39.8 13.4 15.62005-302 1754M 9.3.2009 Purukeitto lw 40.9 6 35 4.5 180 1050 41.7 0.10 41.8 24.5 40.7 13.4 15.02005-302 1748M 4.3.2009 Purukeitto lw 40.9 6 35 4.5 180 1200 41.0 0.01 41.1 20.6 42.6 13.4 13.92005-302 1766M 1.4.2009 Purukeitto ref dry 91.8 6 35 4.5 180 900 44.4 0.04 44.5 28.8 32.8 13.3 14.42005-302 1769M 1.4.2009 Purukeitto ref dry 91.8 6 35 4.5 180 1050 43.8 0.06 43.8 25.7 34.0 13.2 13.32005-302 1768M 1.4.2009 Purukeitto ew dry 90.1 6 35 4.5 180 1000 42.6 0.04 42.6 27.1 39.1 13.3 15.22005-302 1771M 1.4.2009 Purukeitto ew dry 90.1 6 35 4.5 180 1200 42.0 0.04 42.0 22 41.5 13.3 13.82005-302 1767M 1.4.2009 Purukeitto lw dry 91.9 6 35 4.5 180 850 42.8 0.06 42.9 29 38.7 13.3 15.82005-302 1770M 1.4.2009 Purukeitto lw dry 91.9 6 35 4.5 180 1050 41.8 0.04 41.8 24.3 40.7 13.3 14.0

CHIP DATA CHEMICAL CHARGE TEMPERATURE PULP BLACK LIQUOR

58 (59) Appendix 1

Table 11. Pulp properties.Ew Ref Lw

SampleNumber of

tests 1749 m1753 m1754 mWet disintegration of chemical pulp ISO 5263-1:2004Fibre distribution, FS-300 - Arithmetic av. fibre length, mm 0.70 0.79 0.72 - Length weighted av. fibre length, mm 1.53 1.66 1.54 - Weight weighted av. fibre length, mm 2.13 2.26 2.19 - Length < 0,2 mm, % 5.36 4.17 4.46 - Fiber curl, % 7.5 7.7 7.1 - Kink index, 1/m 350 375 349 - Fiber width, µm 24.8 25.1 24.8Grammage, g/m² *) ISO 5270:1998 66.1 66.3 66.4Bulking thickness, µm *) ISO 5270:1998, ISO 534:1988 5 87.4 100 106Standard deviation, µm 1.7 2 3Apparent bulk-density, kg/m³ *) ISO 5270:1998, ISO 534:1988 5 756 661 629Standard deviation, kg/m³ 14 13 15Bulk, cm³/g *) ISO 534:1988 5 1.32 1.51 1.59Standard deviation, cm³/g 0.03 0.03 0.04Tensile strength, kN/m *) ISO 5270:1998, EN ISO 1924-2:1994 10 5.84 4.48 4.10Standard deviation, kN/m 0.25 0.17 0.13Tensile index, Nm/g *) ISO 5270:1998, EN ISO 1924-2:1994 10 88.4 67.5 61.7Standard deviation, Nm/g 3.8 2.6 1.9Stretch, % *) ISO 5270:1998, EN ISO 1924-2:1994 10 2.6 2.3 2.2Standard deviation, % 0.2 0.2 0.1Tensile energy absorption, J/m² *) EN ISO 1924-2:1994 10 103 70.0 62.9Standard deviation, J/m² 12 9.1 5.0TEA index, J/g *) EN ISO 1924-2:1994 10 1.57 1.06 0.948Standard deviation, J/g 0.18 0.14 0.075Tensile stiffness, kN/m *) EN ISO 1924-2:1994 10 606 511 483Standard deviation, kN/m 10 11 14Tensile stiffness index, kNm/g *) EN ISO 1924-2:1994 10 9.17 7.70 7.27Standard deviation, kNm/g 0.16 0.17 0.21Modulus of elasticity, N/mm² *) EN ISO 1924-2:1994 10 6934 5095 4571Standard deviation, N/mm² 120 111 129Tearing strength, mN *) ISO 5270:1998, ISO 1974:1990 5 583 833 881Standard deviation, mN 14 24 40Tear index, mNm²/g *) ISO 5270:1998, ISO 1974:1990 5 8.82 12.6 13.3Standard deviation, mNm²/g 0.21 0.4 0.6

Arrival date:25.5.2009Date of tests: 26.5.2009/askTest conditions: 50% RH, 23°CApproval: 26.5.2009 ELK

Compared at a constant H-factor, the lw-fraction was cooked to lower kappa number than ew-fraction (Fig.70). When air-dried raw materials were use, the difference was much smaller.The yield of lw-pulps was lower than that of ew-pulps (Fig. 70 left). Both fractions gotsmaller yield than the reference indicating that something was lost or some reactions havetaken place during the fractionation and washing processes. This has also affected the higherbrightness of the fraction-pulps (Fig.70 right).

59 (59) Appendix 1

The viscosities of the pulps at kappa level 25 were 920 (ref), 890 (ew) and 900 (lw) indicatingthat the yield loss is not because of excess dissolving of hemicelluloses (the viscosity of thefraction-pulps is not higher than that of the reference).

20

25

30

35

40

700 800 900 1000 1100 1200 1300

Ka

pp

a n

um

be

r

H-factor


Figure 69. Kappa number as a function of H-factor.

40

41

42

43

44

45

46

20 25 30 35 40

Yie

ld %

Kappa number


30

35

40

45

20 25 30 35 40

Bri

gh

tne

ss %

Kappa number


Figure 70. Total yield and pulp brightness as a function of kappa number.

Both fraction-pulps had 0.1 mm lower fibre length than the reference, Table 4. In general, se-vere fibre cutting has taken place already during the preparation of the pin chips (initial fibrelength ca. 2.5 mm). The density of the laboratory sheets made of ew-pulp had much higherdensity, higher tensile and lower tear index than the lw-pulp. In general, the lw-pulp proper-ties were closer to the reference pulp, but the ew-pulp was clearly different.

Table 12. Fiber length and sheet properties of the cooked pulps.

Sample ref ew lwFiber length, lw, FS300, mm 1.66 1.53 1.54Apparent bulk-density, kg/m³ 661 756 629Tensile index, Nm/g 67.5 88.4 61.7Stretch, % 2.3 2.6 2.2Tear index, mNm²/g 12.6 8.82 13.3

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New value chains – - VTT.fi | VTT - Teknologiasta tulosta value chains/Wood fractionation 28180/FFS Author(s) Pages Kari Edelmann, Juha Heikkinen, Sari Liukkonen, Veli Seppänen